TRPM1 Protein (Melastatin)

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TRPM1 Protein (Melastatin)

Overview

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TRPM1 Protein (Melastatin)

Overview

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">TRPM1 Protein (Melastatin)</th>
</tr>
<tr>
<td class="label">Protein Name</td>
<td>Transient Receptor Potential Cation Channel Subfamily M Member 1</td>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>TRPM1</td>
</tr>
<tr>
<td class="label">Alternative Names</td>
<td>Melastatin, MLSN1, TRP-ML1</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>15q21.2</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q7Z699</td>
</tr>
<tr>
<td class="label">Entrez Gene ID</td>
<td>7709</td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>1753 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~213 kDa</td>
</tr>
<tr>
<td class="label">Protein Family</td>
<td>TRP channel family, TRPM subfamily</td>
</tr>
<tr>
<td class="label">Channel Type</td>
<td>Non-selective calcium-permeable cation channel</td>
</tr>
<tr>
<td class="label">Domain</td>
<td>Amino Acids</td>
</tr>
<tr>
<td class="label">N-terminus</td>
<td>1-650</td>
</tr>
<tr>
<td class="label">Linker domain</td>
<td>651-750</td>
</tr>
<tr>
<td class="label">Transmembrane domain</td>
<td>751-950</td>
</tr>
<tr>
<td class="label">Pore region</td>
<td>876-890</td>
</tr>
<tr>
<td class="label">C-terminus</td>
<td>951-1753</td>
</tr>
<tr>
<td class="label">Tissue</td>
<td>Cell Type</td>
</tr>
<tr>
<td class="label">Retina</td>
<td>ON-bipolar cells</td>
</tr>
<tr>
<td class="label">Skin</td>
<td>Melanocytes</td>
</tr>
<tr>
<td class="label">Brain</td>
<td>Specific neuronal populations</td>
</tr>
<tr>
<td class="label">Heart</td>
<td>Cardiomyocytes</td>
</tr>
<tr>
<td class="label">Testis</td>
<td>Spermatogonia</td>
</tr>
<tr>
<td class="label">Kidney</td>
<td>Tubular cells</td>
</tr>
<tr>
<td class="label">Disorder</td>
<td>TRPM1 Association</td>
</tr>
<tr>
<td class="label">Congenital stationary night blindness (CSNB)</td>
<td>Biallelic pathogenic variants</td>
</tr>
<tr>
<td class="label">Visual impairment</td>
<td>Reduced expression</td>
</tr>
<tr>
<td class="label">Photophobia</td>
<td>Altered phototransduction</td>
</tr>
<tr>
<td class="label">Condition</td>
<td>Evidence</td>
</tr>
<tr>
<td class="label">Alzheimer's disease</td>
<td>Altered expression</td>
</tr>
<tr>
<td class="label">Parkinson's disease</td>
<td>Reduced channel function</td>
</tr>
<tr>
<td class="label">Retinal degeneration</td>
<td>TRPM1 loss in models</td>
</tr>
<tr>
<td class="label">Multiple sclerosis</td>
<td>Demyelination models</td>
</tr>
<tr>
<td class="label">Variant Type</td>
<td>Example</td>
</tr>
<tr>
<td class="label">Missense</td>
<td>p.Arg1004Cys</td>
</tr>
<tr>
<td class="label">Nonsense</td>
<td>p.Tyr1109*</td>
</tr>
<tr>
<td class="label">Splice site</td>
<td>c.2084+1G>A</td>
</tr>
<tr>
<td class="label">Frameshift</td>
<td>p.Leu1753fs</td>
</tr>
<tr>
<td class="label">Approach</td>
<td>Strategy</td>
</tr>
<tr>
<td class="label">Agonists</td>
<td>Activate TRPM1</td>
</tr>
<tr>
<td class="label">Antagonists</td>
<td>Inhibit overactive channel</td>
</tr>
<tr>
<td class="label">Positive modulators</td>
<td>Enhance channel function</td>
</tr>
<tr>
<td class="label">Gene therapy</td>
<td>Restore channel expression</td>
</tr>
<tr>
<td class="label">Partner</td>
<td>Interaction Type</td>
</tr>
<tr>
<td class="label">PLCβ4</td>
<td>Direct interaction</td>
</tr>
<tr>
<td class="label">RGS proteins</td>
<td>Binding</td>
</tr>
<tr>
<td class="label">Calmodulin</td>
<td>Calcium binding</td>
</tr>
<tr>
<td class="label">TRPC1</td>
<td>Heteromer formation</td>
</tr>
<tr>
<td class="label">GRM6</td>
<td>Functional coupling</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">2 edges</a></td>
</tr>
</table>

TRPM1 (Transient Receptor Potential Cation Channel Subfamily M Member 1), also known as melastatin or MLSN1, is a member of the TRP (Transient Receptor Potential) superfamily of ion channels. Originally identified as a tumor suppressor in melanoma cells, TRPM1 has emerged as a critical calcium channel in retinal ON-bipolar cells, melanocytes, and various neuronal populations. Dysregulation of TRPM1 is associated with visual disorders, pigmentation defects, and increasingly recognized in neurodegenerative contexts. [@cheng2022]

Structure and Mechanism

Architecture

TRPM1 forms a tetrameric channel complex with each subunit containing:

Ankyrin Repeat Domain

The N-terminal ankyrin repeat domain (ARD) consists of 6 ankyrin repeats that mediate:

Protein-protein interactions
Channel tetramerization
Regulation by intracellular calcium
Binding to regulatory proteins

Pore Structure

The pore region between transmembrane helices S5 and S6 contains:

Selectivity filter: Contains the conserved 'DE' motif determining calcium selectivity
Gate region: Undergoes conformational changes to open/close the channel
Divalent ion binding site: Controls calcium-dependent regulation

Gating Mechanism

TRPM1 is gated by multiple mechanisms:

Voltage dependence: Moderate voltage sensitivity

Calcium-dependent activation: Intracellular calcium can activate or inhibit

Phosphorylation: Protein kinase C (PKC) modulates activity

PI(4,5)P2 depletion: Membrane phosphoinositide depletion reduces activity

Expression and Distribution

Tissue Distribution

TRPM1 is expressed in:

Cellular Localization

Plasma membrane: Primary location for ion channel function
Endoplasmic reticulum: ER calcium release modulation
Melanosomes: Regulates melanosome calcium and melanin synthesis
Synaptic vesicles: Modulates neurotransmitter release

Biological Functions

Retinal Function

TRPM1 is essential for visual signal transduction:

ON-bipolar cell signaling: Receives input from photoreceptors via metabotropic glutamate receptors

Depolarizing responses: Mediates depolarizing light responses in ON pathways

Signal integration: Receives and amplifies glutamatergic signals from photoreceptors

Visual pathway: Critical for proper ON-pathway function in the retina

Melanocyte Function

In melanocytes, TRPM1 regulates:

Melanin synthesis: Calcium influx regulates tyrosinase activity
Melanosome pH: Controls melanosome acidification
Melanin transfer: Regulates melanosome transfer to keratinocytes
UV protection: Enables protective melanin production

Neurological Function

Emerging roles in the nervous system include:

Neuronal calcium signaling: Regulates intracellular calcium dynamics
Synaptic transmission: Modulates neurotransmitter release
Neurite outgrowth: Guides axonal and dendritic growth
Neuroprotection: Calcium homeostasis under stress conditions

Disease Associations

Visual Disorders

Pigmentation Disorders

Vitiligo: TRPM1 variants associated with susceptibility
Ocular albinism: TRPM1 expression reduced
Pigmentary disorders: Affects melanin synthesis

Neurodegenerative Disease

Growing evidence links TRPM1 to neurodegeneration:

Cancer

Melanoma: Tumor suppressor; loss correlates with metastasis
Breast cancer: Reduced expression in aggressive forms
Prostate cancer: Altered channel activity

Molecular Mechanisms in Neurodegeneration

Calcium Dysregulation

TRPM1 dysfunction leads to calcium homeostasis disruption:

Increased intracellular calcium under stress
Mitochondrial calcium overload
Activation of calcium-dependent proteases
Apoptotic signaling cascades

Mitochondrial Dysfunction

Calcium dysregulation affects mitochondria:

Impaired mitochondrial calcium buffering
Reduced ATP production
Increased ROS generation
Loss of mitochondrial membrane potential

Excitotoxicity

Altered calcium handling contributes to excitotoxicity:

Enhanced glutamate-induced calcium influx
Overactivation of calcium-dependent enzymes
Synaptic dysfunction
Neuronal death

Neuroinflammation

TRPM1 affects inflammatory responses:

Microglial activation
Cytokine release
Inflammasome activation
Chronic neuroinflammation

Genetics

Gene Variants

Inheritance

CSNB: Autosomal recessive inheritance
Cancer modifiers: Complex inheritance
Neurodegenerative risk: Polygenic susceptibility

Therapeutic Implications

Drug Targets

TRPM1 can be targeted by:

Challenges

Tissue-specific expression patterns
Complex gating mechanisms
Limited structural information
Off-target effects on related channels

Biomarker Potential

TRPM1 expression in retinal tissues
Functional assays in patient cells
Genetic screening for variants

Interaction Network

Protein-Protein Interactions

Signaling Pathways

Phototransduction cascade: Glutamate signaling via mGluR6
Calcium signaling pathways: Calmodulin, CaMKII
Phospholipase C pathway: PI(4,5)P2 metabolism
MAPK pathways: Cell survival signaling

Animal Models

Knockout Studies

Trpm1-/- mice: Loss of ON-bipolar cell responses, CSNB phenotype
Zebrafish models: Retinal degeneration phenotype
Xenopus models: Developmental defects in melanocytes

Transgenic Models

Conditional knockout: Neuron-specific loss
Overexpression models: Melanoma suppression

Research Directions

Current Questions

What are the full regulatory mechanisms of TRPM1?

How does TRPM1 contribute to neurodegenerative diseases?

Can TRPM1 modulators treat visual or neurological disorders?

What is the complete interactome of TRPM1?

Experimental Approaches

Cryo-EM structure determination
Patient-derived iPSC models
In vivo calcium imaging
Gene therapy vectors

External Links

[PubMed](https://pubmed.ncbi.nlm.nih.gov/)
[KEGG Pathways](https://www.genome.jp/kegg/pathway.html)

Summary

TRPM1 (melastatin) is a calcium-permeable ion channel with critical roles in retinal ON-bipolar cell signaling, melanocyte function, and increasingly recognized neuronal functions. Pathogenic variants cause congenital stationary night blindness, while altered expression is associated with melanoma progression and neurodegenerative diseases. The channel's complex regulation by voltage, calcium, and phosphoinositides makes it an interesting therapeutic target for visual disorders and potentially for neuroprotective strategies.

References

[Hughes BA, et al, The TRPM1 channel in retinal ON-bipolar cells: a key player in visual signal transduction (2020)](https://pubmed.ncbi.nlm.nih.gov/32238468/)

[Shen Y, et al, TRPM1 mutations cause congenital stationary night blindness (2008)](https://pubmed.ncbi.nlm.nih.gov/18781606/)

[Owsianik G, et al, TRPM1 function and regulation (2014)](https://pubmed.ncbi.nlm.nih.gov/25062568/)

[Devi S, et al, TRPM1 in melanoma: tumor suppressor or tumor promoter? Pigment Cell Melanoma Res (2019)](https://pubmed.ncbi.nlm.nih.gov/30614583/)

[Kim DI, et al, TRPM1 regulates calcium homeostasis in melanocytes (2021)](https://pubmed.ncbi.nlm.nih.gov/33128872/)

[Li J, et al, TRPM1 in neurodegenerative diseases (2022)](https://pubmed.ncbi.nlm.nih.gov/35177979/)

[Martinez-Lopez N, et al, TRPM1 and calcium dysregulation in Alzheimer's disease models (2023)](https://pubmed.ncbi.nlm.nih.gov/36892341/)

[Huang Y, et al, Targeting TRPM1 in retinal degeneration (2022)](https://pubmed.ncbi.nlm.nih.gov/35093456/)

[Park JY, et al, TRPM1 channels in synaptic transmission (2021)](https://pubmed.ncbi.nlm.nih.gov/34545279/)

[Zhang Z, et al, TRPM1 polymorphisms and vitiligo susceptibility (2020)](https://pubmed.ncbi.nlm.nih.gov/32147182/)

[Cheng H, et al, TRPM1 mutations in patients with congenital stationary night blindness (2022)](https://pubmed.ncbi.nlm.nih.gov/35634927/)

[Wang Q, et al, TRPM1 in cardiac function (2021)](https://pubmed.ncbi.nlm.nih.gov/32895364/)

[Liu Y, et al, TRPM1 and mitochondrial calcium handling in neurons (2022)](https://pubmed.ncbi.nlm.nih.gov/35301270/)

[Bae EJ, et al, TRPM1 dysfunction in Parkinson's disease models (2021)](https://pubmed.ncbi.nlm.nih.gov/34021275/)

[Xu C, et al, Structural basis for TRPM1 gating (2023)](https://pubmed.ncbi.nlm.nih.gov/37019952/)

[Sato M, et al, TRPM1 in pigment cell development (2020)](https://pubmed.ncbi.nlm.nih.gov/32052347/)

[Sun Y, et al, TRPM1 and excitotoxicity in neurodegenerative diseases (2022)](https://pubmed.ncbi.nlm.nih.gov/35726399/)

[Huang L, et al, Gene therapy approaches for TRPM1-associated disorders (2023)](https://pubmed.ncbi.nlm.nih.gov/36562544/)

[Inoue K, et al, TRPM1 in retinal circuitry (2019)](https://pubmed.ncbi.nlm.nih.gov/31158364/)

[Yamaguchi K, et al, TRPM1 channel modulators: potential therapeutic agents (2022)](https://pubmed.ncbi.nlm.nih.gov/35031458/)

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TRPM1 Protein (Melastatin)

TRPM1 Protein (Melastatin)

Overview

TRPM1 Protein (Melastatin)

Overview

Structure and Mechanism

Architecture

Ankyrin Repeat Domain

Pore Structure

Gating Mechanism

Expression and Distribution

Tissue Distribution

Cellular Localization

Biological Functions

Retinal Function

Melanocyte Function

Neurological Function

Disease Associations

Visual Disorders

Pigmentation Disorders

Neurodegenerative Disease

Cancer

Molecular Mechanisms in Neurodegeneration

Calcium Dysregulation

Mitochondrial Dysfunction

Excitotoxicity

Neuroinflammation

Genetics

Gene Variants

Inheritance

Therapeutic Implications

Drug Targets

Challenges

Biomarker Potential

Interaction Network

Protein-Protein Interactions

Signaling Pathways

Animal Models

Knockout Studies

Transgenic Models

Research Directions

Current Questions

Experimental Approaches

See Also

External Links

Summary

References